Biopsies and other techniques are commonly performed to remove a tissue sample from a selected site within the body. The sample may then be examined and analyzed. Many biopsy devices make use of a hollow tube that forms a working channel. The hollow tube is inserted into the site from where the sample is to be taken. The hollow tube frequently includes an aperture in communication with the working channel. The aperture provides access between the working channel and the site to be analyzed, which may be at some sub-cutaneous depth. This access allows samples to be taken from the desired location.
In particular, the aperture is placed adjacent to the site from which the sample is to be taken. Thereafter, the tissue is drawn through the aperture and into the working channel, such as through the use of a vacuum. A thin tube commonly referred to as a cutting cannula is then pushed through the working channel. The cutting cannula is sized to fit closely to the inner wall of the working channel. Thus, as the cutting cannula is passed over the aperture, the cutting cannula cuts the tissue extending into the working channel. The tissue may then be removed and examined.
It may be desirable to identify or “mark” the location of the biopsy site at some later point. For example, it may be desirable to have the ability to return to the same site, such as to take further samples and/or to provide further treatment to an affected area. In order to identify the biopsy site, markers may be used. The markers frequently include a relatively small device or material that is readily identifiable. The markers are often introduced using a deployment device in conjunction with the working channel of the biopsy device.
When introduced through the working channel of a biopsy device, current marker deployment devices do not effectively close off the aperture, resulting in gaps or dead space between the biopsy device and the marker device. This creates the potential for the marker to fall partially or completely back into the aperture of the biopsy device. As a result, the marker can be pulled out of the biopsy site when the biopsy device is removed. This is known as “drag out.” Drag out can lead to the biopsy site not being identified, an incorrect area of tissue being identified, and treatment of the wrong site.